Given parameters:
Actual length = 260m
Drawing length = 286mm
Unknown:
Scale used = ?
Solution:
A scale compares drawing length to ground distance;
To find the scale,
Express the two quantities in the same unit;
actual length = 260 x 10⁻³m = 0.26mm
Now;
drawing length : actual length
286mm : 260 x 10⁻³mm
divide by 286;
1mm on drawing : 9 x 10⁻⁴mm on map
or;
1mm on drawing is 0.9m on ground